<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function calculate(method,...nums){
            let result;
            if(!method||nums.length==0){
                alert('请传入参数！');
                return;
            }
            if(method=='*'){
                result=1;
                for(let i=0;i<nums.length;i++){
                    result *=nums[i];
                }
            }else if(method=='+'){
                result=0;
                for(let i=0;i<nums.length;i++){
                    result += nums[i];
                }
            }
            alert(result);
        }
        calculate("+",1,2);
        calculate("+",1,2,3,4,5);
        calculate("*",1,2,3);
        calculate("*",1,2,3,4,5);
    </script>
</body>
</html>